graphql/src/Language/GraphQL.hs

-- | This module provides the functions to parse and execute @GraphQL@ queries.
module Language.GraphQL
    ( graphql
    , graphqlSubs
    ) where

import qualified Data.Aeson as Aeson
import Data.HashMap.Strict (HashMap)
import Data.Text (Text)
import Language.GraphQL.AST.Document
import Language.GraphQL.AST.Parser
import Language.GraphQL.Error
import Language.GraphQL.Execute
import Language.GraphQL.Execute.Coerce
import Language.GraphQL.Type.Schema
import Text.Megaparsec (parse)

-- | If the text parses correctly as a @GraphQL@ query the query is
-- executed using the given 'Schema.Resolver's.
graphql :: Monad m
    => Schema m -- ^ Resolvers.
    -> Text -- ^ Text representing a @GraphQL@ request document.
    -> m Aeson.Value -- ^ Response.
graphql = flip graphqlSubs (mempty :: Aeson.Object)

-- | If the text parses correctly as a @GraphQL@ query the substitution is
-- applied to the query and the query is then executed using to the given
-- 'Schema.Resolver's.
graphqlSubs :: (Monad m, VariableValue a)
    => Schema m -- ^ Resolvers.
    -> HashMap Name a -- ^ Variable substitution function.
    -> Text -- ^ Text representing a @GraphQL@ request document.
    -> m Aeson.Value -- ^ Response.
graphqlSubs schema f
    = either parseError (execute schema f)
    . parse document ""